Questions tagged [moons]

For questions pertaining to natural satellites, such as our own Moon.

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113
votes
6answers
36k views

How would having multiple moons affect tides?

We know that planets can have multiple moons, sometimes quite a few (like Jupiter). Assuming that a planet with several moons were habitable in the first place and has significant oceans (greater ...
98
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6answers
23k views

Would a Moon made of water pose a threat to Earth during eclipses?

Is a moon made entirely of water possible? Could a planet made completely of water exist? I was inspired by the above questions to ask the following: Assume that our current Moon is replaced ...
58
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20answers
13k views

What could a self-sustaining lunar colony slowly lose that would ultimately prove fatal?

I've got a lunar colony that was set up to be self-sustaining before a collapse of life on Earth. The colony has survived on its own for several thousand years through a period of technological ...
57
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16answers
9k views

Speedrun to the moon in one lifetime?

Imagine you have a large population of adolescent humans (as large as you need) on a completely uncultivated Earth, initially containing no artificial structures whatsoever, only natural resources. ...
50
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7answers
10k views

Can I use a trebuchet to launch satellites into space from a lunar colony?

I've got a lunar colony that struggles to obtain resources, so they're looking for ways to launch satellites into orbit without using up a bunch of rocket fuel. One plucky engineer has suggested ...
49
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4answers
6k views

Moons of Moons of Moons

My question is simple: How many nested moons are physically possible? If our moon had a moon, that would be a nesting of 1. I'm assuming it's easily possible for a really big moon to be orbiting a ...
40
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14answers
6k views

Moon that changes color with phase

In a world I am building, I would like to have the moon change color when seen from the planet's surface as it goes through its phases (e.g., the crescent after new moon is blood red, a quarter moon ...
39
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3answers
9k views

Habitable moon of a gas giant: working out the sizes and distances

I am attempting to create fictional, stable P-Type binary system, featuring a gas giant in a stable orbit, with a habitable Earth-like moon. “Is a Jupiter-sized planet plausible in a habitable zone?” ...
35
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6answers
6k views

What's the smallest reasonable natural planet or moon with Earth-like surface gravity?

We all know that equation for surface gravity is $$ g = \frac{4\pi}{3} G \rho r $$ So if we want Earth-like surface gravity of $ g = 9.81 $, then the equation for radius is $$ r = \frac{3 g}{4\pi G ...
34
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12answers
8k views

How would one design an undetectable nuke to hit the Moon with?

Colonists have set up a viable, long term lunar colony on the near-side of the moon in the mid-21st century. They are quickly reaching total self-sufficiency and the earth governments who sponsored ...
34
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7answers
5k views

Can a radioactive moon affect life on a planet?

This question is meant as a reality check on this answer to The land grows evil and corrupted ... but why? Radioactive moon in a nearly geosynchronous orbit. It slowly kills or alters all life ...
33
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11answers
8k views

Where is the best place to park your damaged spaceship, longterm?

Your large spaceship is damaged beyond repair. You manage to get it close enough to a planet so that you can release emergency shuttle craft. You have very little control over the ship and won't be ...
33
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6answers
7k views

How big could an alien-made object on the far side of the moon become so that discovery still can only happen by accident?

A great way to introduce advanced technology to a story is to have it be of extraterrestrial origin. E.g. have a spaceship crash on earth, or, like I was planning to, put a derelict spaceport on the ...
33
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11answers
7k views

What skin colour would living permanently on the moon select for?

The context: There is a population of people surviving on a lunar-analogue's surface, descended from the crew of a crashed spaceship. The rest of their society is not relevant to the question, but ...
32
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8answers
6k views

Can we 'beam' energy from the moon?

Really can't believe I have to edit this in, but this question has no bearing on our current use and generation of nuclear energy on Earth. There are dangers to nuclear energy generation, or we would ...
31
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5answers
11k views

If Sweden was to magically float away, at what altitude would it be visible from the southern hemisphere?

If a chunk of land mass the size and position of Sweden took off and floated away in a straight line, exiting the atmosphere and orbiting earth, at what distance would it be visible from, let's say, ...
30
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12answers
6k views

How to wrap the Moon in plastic to make her a giant, supported by the atmospheric pressure, greenhouse

Moon's surface is about thirty million square kilometers large. That's a lot of plastic, but no bigger effort than many other terraforming projects we have discussed. Description: A global bubble ...
29
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5answers
6k views

How deep must be a pit on the moon to hold atmosphere at 1ATM on the bottom

In my world I would like to create a pit on the Moon filled with air. How deep would the pit need to be to get 1 ATM of pressure Could the pit maintain the air or would it be lost to space? If it ...
28
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12answers
9k views

Would gas giants work as waste disposal sites?

In my novel, the many moons of Jupiter and Saturn have been colonized, but I'm running into some logistical problems - namely, waste disposal. My first instinct was to dump it on-moon; while this is ...
28
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12answers
2k views

How can spacecraft manufactured on the moon be powered?

Background: The moon has been selected as the base for human space exploration. Rather than ship tonnes of material out of earth's gravity well, interplanetary spacecraft and space stations will be ...
27
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5answers
2k views

Can you add a mini moon to Earth?

So we have had multiple questions on having multiple moons and this is another. I did check and didn't find questions that covered this specific setup. I have an earth-like world I am working on, ...
25
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10answers
7k views

How would you build a harbor in a world with *intense* tides?

Long story short, my world is set on a habitable moon of a gas giant, and as a result has some very intense tides (about 5x those of Earth, averaging a few dozen foot difference between high and low ...
23
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7answers
7k views

How big can a moon be where you can physically jump out of its orbit, to its planet?

So, imagine a team of space marines, fighting some sort of space bug zombies on a planet's moon. Things are going pretty bad for them, and the last surviving protagonists are running for their lives. ...
23
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5answers
5k views

What would a habitable moon most probably look like?

We have a pretty good idea of what attributes a planet would need to sustain life and one can imagine how life might develop on a planet, even in difficult environments. I find it extremely difficult ...
22
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13answers
5k views

Always a full Moon for the Emperor - Can this be achieved with solar panels and LEDs?

The Emperor of the World wants there always to be a full moon. His Scientific Advisor (the SA) comes up with a plan. He plans to cost out the venture, hand it over to the Keeper of the Treasury who ...
22
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3answers
3k views

Reality Check: Habitable moon around earth-like planet

For a complex world-building scenario I want a habitable moon orbiting a habitable earth-like planet. The habitable moon should allow for flora, fauna and landscape as similar to earth as possible. ...
22
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3answers
3k views

Realistic sky of an Earth-like moon orbiting a gas giant (length of day and size of celestial bodies)

I'm trying to work out what the sky looks like on an Earth-like moon, in particular the length of day and apparent size of the other celestial bodies: the gas giant's size, the gas giant's other moon'...
21
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15answers
4k views

How can a spaceship unknowingly interfere with tides on a planet?

I've asked before about my polytheists with competing moon gods. I now have a better understanding of how tides -- a very visible manifestation of lunar influence -- work with multiple moons (thanks),...
21
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5answers
4k views

Would a planet appear to wax and wane as observed from its moon?

Assuming that the observer is on the moon for a full lunar cycle, would the appearance of the planet wax and wane, would the moon's shadow occlude the planet during an eclipse while on the moon?
21
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3answers
3k views

That's no moon! It's a space station! How big can a space ship be before it collapses on itself?

Now a solid body of rock will collapse itself to a round shape when it hits about 600 km in diameter (400 km for ice). Now, the Second Death Star is estimated to be between 160 and 900 km. How big can ...
19
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25answers
5k views

What might cause a civilization to be unable to colonize a large moon but live in space stations around it instead?

In my world a moon is reached and colonised but only in space stations for a long time. They gain the ability to reach the surface and then story happens. It needs to be something that can be bypassed ...
19
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13answers
3k views

Terminology for 24 hour wake-sleep cycle on world with longer dark-light cycle?

Take the Jovian moon Ganymede as a real-world example. It has an orbital period of ~7 days around Jupiter, which is effectively its day and its year simultaneously. My characters will need the words ...
19
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7answers
6k views

How would a planet-sized computer power receive power?

Imagine: A Kardashev Type I civilization mainly resides on a planet analogous to Earth, with one moon, analogous to Earth's moon. Eventually, the society grows so complex that machines filling space ...
19
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4answers
1k views

Earth-like Moon around the Gas Giant. Eclipse length?

Worldbuilder in dire need! I'm trying to figure out the eclipse length of a habitable Earth-like moon that is rotating around a gas giant. The story that I work on is centered on the Earth-like moon, ...
19
votes
4answers
725 views

Making doomsayers right - a moon(s), planet alignment that matters

Considering our topic challenge, and the fantastic eclipse last Sunday a question came to me. Could there be a stable (relatively speaking) planetary system where a(n) eclipse/alignment would ...
18
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9answers
6k views

Is a moon inside a hollow Earth possible?

The Hollow Earth theory is/was a pseudoscientific idea that our world is actually on the inside of a large sphere. The "sky" points inward towards the center, where the "Sun" (a light source) is, ...
18
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2answers
3k views

Tidally locked gas giant moon - brightness of the gas giant

Imagine a tidally locked gas giant moon, which is otherwise earth-like. One side of the moon will have a huge planet constantly hovering in the sky (24 hour day/night cycle with a Jupiter-sized ...
18
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9answers
4k views

What kind of event, if any, would knock the moon off its orbit, without destroying it?

I am recalling the Space:1999 nuclear waste containment explosion; this has been criticized because such an explosion would have actually destroyed the moon. I am curious for events that could happen ...
18
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1answer
1k views

Can a habitable moon rely on the magnetosphere of its parent planet for radiation protection?

Science-based answers, please. Key points: the main concern is radiation protection for sustainability of human life (and accompanying plant and animal life ecosystems, whether earth-like or not). ...
17
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3answers
5k views

Are moons always the same colour?

When viewed from their planet, are moons always the same colour as ours? Or is there a variation? What other colours might be possible and what causes the differences in colour?
17
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3answers
1k views

Can we breathe the moon's crust?

According to this answer to what the moon is made of, the moon's crust is, among other things, 43% oxygen. Assuming we were to go back to the moon within the next couple of years with the goal of ...
16
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10answers
7k views

Could humans alter the moon's orbit significantly with current technology?

A terrible virus has made most of the populations and government officials of the largest superpowers on Earth stark, raving mad, without depriving them of their intelligence. They have decided that ...
16
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7answers
4k views

How to flood the entire lunar surfaces?

Given that the surface gravity on the Moon is a fraction of Earth and there is virtually zero atmospheric pressure but I still want to wet our beloved moon with whatever liquid that is known to ...
16
votes
7answers
2k views

Colony on the moon - how fast can Santa deliver?

I sometimes tell my kid that when he grows up, he might be living on the moon. Last night he was worried that Santa won't be able to bring him presents there. To which I replied that sure, Santa can ...
16
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4answers
5k views

By what mechanism could a planet be locked into permanent solar eclipse?

I've got an image in my head of a world where it's just normal that the star is black with a golden halo around it - in other words, where the planet is in a state of perpetual solar eclipse. Are ...
15
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13answers
12k views

Is stealing the moon actually possible?

I'm writing a heist story set in the near future. The goal of my main protagonists is to actually steal the Moon. The budget of their escapade is not a variable; they will get this done however ...
15
votes
17answers
4k views

What would cause a moon to become much brighter only a few times a year?

I initially wanted to create a culture that used tides to tell the seasons, I'm sure I still can, but a question on here (I can no longer find it) made me wonder if I could set up a world where one of ...
15
votes
8answers
2k views

How to explain life on a moon orbiting a non-habitable planet

For story purposes, I am building a world where all life exists on the moon of a non-habitable planet (the moon is not tidally locked). How can I explain this in a convincing and mostly scientific way?...
15
votes
6answers
2k views

Can there be a moon within a planetary ring?

A simple question, could a moon exist and stay whole if it was inside the ring of asteroids orbiting a planet? And as a side note, would it create a kind of bulge in the ring where the asteroids ...
15
votes
8answers
6k views

Power cable from earth to the moon?

Related Question : Can we 'beam' energy from the moon? I was wondering if instead of 'beam'ing energy from the moon, could it be possible to extend a power cable from the earth to the moon? If the ...

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